1. Field of the Invention
This invention relates to a semiconductor module and a radiator plate used therein, and more particularly to a semiconductor module and a radiator plate used therein in which respective upper surfaces of semiconductor elements on both sides of a rectangular circuit board are covered with the rectangular radiator plates.
2. Description of Related Art
The semiconductor module, in which respective upper surfaces of semiconductor elements on both sides of a rectangular circuit board are covered with rectangular radiator plates, is disclosed in e.g. Japanese Patent Unexamined Publication JP-A-2001-196516.
Such a semiconductor module is shown in FIG. 16. FIG. 16A is a front view of the semiconductor module. FIG. 16B is a transverse sectional view of the semiconductor module. FIG. 16C is a longitudinal sectional view of the semiconductor module.
On a rectangular circuit board 100 constituting the semiconductor module shown in FIG. 16, in the longitudinal direction on both sides thereof, a plurality of semiconductor elements 102, 102, . . . are loaded. At one of the outer peripheral edges along the longitudinal direction, card-edge connectors 100a, 100a are formed. These semiconductor elements 102, 102, . . . are accommodated in accommodating recesses 106 formed in the rectangular radiator plates 104a, 104b attached to board surfaces of the circuit board 100, respectively. The upper surfaces semiconductor elements 102, 102, thus accommodated abut on a bottom surface of the accommodating recess 106. Further, vicinity of an outer peripheral edge of the accommodating recess 106 abuts on the board surface of the circuit board 100 over an entire periphery of the accommodating recess 106.
These radiator plates 104a, 104b are coupled to each other at one of their longer sides in the longitudinal direction pivotally via a hinge 108. The area between the outside of the accommodating recess 106 and the outer peripheral edge of the radiator plate is partially bent so as to abut on the corresponding board surface of the circuit board 100.
These radiator plates 104a, 104b, as seen from FIGS. 16B and 16C, are larger than the circuit board 100. Therefore, as shown in FIG. 16A, both sides of the circuit board 100 are covered with the radiator plates 104a, 104b. Thus, the edge connectors 100a, 100a of the circuit board 100 are exposed and mounting clips 110 on the areas of the radiator plates 104a, 104b projected from the circuit board 100, the radiator plates 104a, 104b can be attached to both side of the circuit board 100.
In the semiconductor module shown in FIG. 16, the radiator plates 104a, 104a can be easily attached to both sides of the circuit board 100.
However, the radiator plates 104a, 104b of the semiconductor module shown in FIG. 16 are attached so that they project from the outer peripheral edges of the circuit board 100.
On the other hand, in a memory module for expansion or addition for a server computer or personal computer, which is generally employed as a semiconductor module, it has been demanded for its miniaturization that the radiator plates are attached to the outer peripheral edges of the circuit board.
Further, in the semiconductor module shown in FIG. 16, the vicinity of the outer peripheral edge of the accommodating recess 106 in the radiator plate 104a, 104b abuts on the board surface of the circuit board 100 over the entire periphery of the accommodating recess 106. Therefore, an abutting area, on which a part of the radiator plate 104a, 104b abuts, must be assured on the board surface of the circuit board 100. This gives rise to a limit for miniaturization of the circuit board 100.
On the other hand, if this accommodating recess 106 is not substantially formed to reduce the contact area between the radiator plate 104a, 104b and the circuit board 100 to the utmost, the semiconductor module can be miniaturized. However, in this case, the semiconductor elements suffer from load applied to the radiator plates. Particularly, at the semiconductor element loaded in the vicinity of the center area of the circuit board 100, the load applied to the radiator plates is apt to concentrate. So when the semiconductor element with low strength is loaded, the semiconductor element may be broken.